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Clinical Trials 101

Before a new therapy is widely available in doctors' offices, it goes through several rounds of carefully regulated testing in people. These happen in three stages:

Phase 1 trials include a very small number of people and are primarily intended to test whether the proposed therapy is safe.

Phase 2 trials include slightly more people and are intended to verify that the therapy is safe, and to start looking into whether it is effective at treating the disease or condition.

Phase 3 trials include large numbers of people and are intended to test whether the therapy effectively treats the disease or condition.

The vast majority of clinical trials carried out in the United States are required to be listed on the clinicaltrials.gov website. However, some of the trials listed on the site charge patients to participate and may be marketing therapies that are not part of a government-sanctioned clinical trial. In addition, some trials being carried out in other countries won't always have additional trial details available through that site.

Patients Interested in Trials

If you’re thinking about taking part in a stem cell clinical trial, it can be difficult finding one that’s right for you. Watch our animated video to learn about the 4 things you should know before you sign up for a trial.

CIRM-Funded Clinical Trials

​Our Agency funds clinical trials that are testing promising stem cell treatments or treatments that act on stem cells to help patients with unmet medical needs.